#include<stdio.h>

int check_sys() {
	union {
		int i;
		char c;
	}un;
	un.i = 1;
	return un.c;
}

int main() {
	char a = -1;
	signed char b = -1;
	unsigned char c = -1;
	printf("a=%d,b=%d,c=%d", a, b, c);
	return 0;
}